Rotary structure

Abstract

This invention relates to a rotary structure adapted to be used as a spindle unit for a miniature motor or miniature rotor or as a tape guide roller for a VTR. In the structure of the rotary mechanism, instead of a conventional expensive radial ball bearing, a substantially V-shaped groove is formed on a shaft itself so as to hold balls provided between this groove and the tapered surface or concave spherical ball receiving surface of an outer race provided around the groove.

What is claimed is: 
     
       1. A rotary structure for a VTR or floppy disc drive comprising a cylindrical shaft having an outer surface provided with a substantially annular V-shaped groove therein, a plurality of balls seated in said groove and projecting beyond an outer surface of the shaft, an outer race surrounding the outer surface of the shaft and having an inner tapered surface in contact with said balls for holding said balls in said groove with a predetermined pressure, a bearing housing surrounding said shaft and having an inner peripheral surface to which said outer race is fixed, said shaft having a second annular V-shaped groove axially spaced from the first said V-shaped groove and a plurality of further balls in said second groove, a second outer race surrounding the outer surface of the shaft and having an inner tapered surface in contact with the balls in the second groove for holding said balls therein under pressure, said second race being fixed to said inner surface of said housing, said V-shaped grooves being substantially adjacent to one another so that the balls in the first and second V-shaped grooves face one another in close proximity. 
     
     
       2. A rotary structure as claimed in claim 1 wherein said shaft and said outer races form small gaps therebetween constituting means for preventing dust passage therethrough. 
     
     
       3. A rotary structure as claimed in claim 1, said shaft having opposite ends projecting from said bearing housing, rotor means on one of said ends of said shaft and pulley means on the other of said ends of the shaft. 
     
     
       4. A rotary structure as claimed in claim 3 wherein said shaft is vertical and said pulley means is at the lower end of the shaft. 
     
     
       5. A rotary structure as claimed in claim 1 wherein the balls in the first and second V-shaped grooves are axially spaced from one another by a distance less than the diameter of said balls. 
     
     
       6. A rotary structure as claimed in claim 1 wherein the inner tapered surfaces of the first and second outer races taper in narrowing fashion towards one another and said races have narrow ends facing one another.